These machines may be synchronous, asynchronous or with direct current. They are operating as a generator or as a motor. In a general manner, they consist of at least one rotor disc and one stator disc.
Such a machine conventionally comprises at least one disc-shaped stator held on a casing and the central portion of which is hollowed out as well as a rotor also in the shape of a disc, mounted onto a shaft the axis of rotation of which coincides with the axis of the stator disc. However, the arrangement of the rotor disc with respect to the stator disc may differ from one discoidal machine to another one.
Thus the patent FR-2,583,231 describes a discoidal machine comprising a rotor disc mounted for rotation on the shaft of the machine and a stator disc connected to the casing and centred onto the axis of the shaft. It also describes a discoidal machine in which a rotor disc is placed between two stator discs. The windings of the rotor and stator discs are placed on confronting faces, the rotor disc being fitted with magnets or windings on these two faces.
One may also refer to the U.S. Pat. No. 4,514,653 which describes an electric machine of the discoidal type comprising several rotor discs and several associated stators.
The U.S. Pat. No. 5,229,677 as to it describes a motor of the discoidal type for marine propulsion.
These documents show that the known discoidal machines are constructed for a given power. Thus to each power corresponds a particular machine comprising a suitable number of rotor and stator discs. Therefore, the components of the machine and in particular the mechanical parts such as the casing for the protection of the motors should be conceived and manufactured for each machine with a given power.
This does not allow to mass-produce the components of the machine. In addition as from its being ordered, the manufacture of a discoidal machine is relatively long lasting.